A method which involves using, as a reaction substrate, aldimine synthesized from an aldehyde and an amine as starting materials to synthesize a racemic compound through a 1,3-dipolar cycloaddition reaction in the presence or absence of a catalyst that promotes the reaction is known as a method for synthesizing a pyrrolidine compound having a bicyclic spirooxindole structure (Non Patent References 1 to 4). The obtained racemic compound can be resolved using a chiral column based on a technique such as HPLC or supercritical fluid chromatography (SFC) to separate a desired optically active form.
An asymmetric synthesis method through a 1,3-dipolar cycloaddition reaction using a chiral element has been reported as a method for stereoselectively synthesizing the compound mentioned above (Non Patent References 5 and 6). In addition, a method for producing a pyrrolidine compound having a tricyclic dispirooxindole structure through a 1,3-dipolar addition reaction using, as a reaction substrate, ketimine synthesized with an amine and a ketone as starting materials has also been reported (Patent Reference 1).
Meanwhile, as for catalytic asymmetric synthesis methods of the compound mentioned above, a large number of studies have been made on catalytic asymmetric 1,3-dipolar cycloaddition reactions using aldimine as a reaction substrate (Non Patent References 7 to 18). Nonetheless, no report has been made on the synthesis of a tricyclic dispiroindole using ketimine with a ketone and an amine as reaction substrates.